Relationship Between Renal Function and Pharmacokinetics of Apixaban and Clinical Outcome of Apixaban in Thai Non-valvular Atrial Fibrillation Patients

Part I Inclusion Criteria: * Patients with nonvalvular atrial fibrillation * Patients who is receiving a stable dose of apixaban for primary or secondary prevention of stroke, transient ischemic attack, and systemic embolism. Exclusion Criteria: * Pregnant or lactating * End stage renal disease patients who required chronic renal replacement therapy to sustained life * History of acute kidney injury within the previous 3 months * Severe hepatic impairment (Child-Pugh class C) * Any gastrointestinal disorder that could impact the absorption of study drug * CYP3A4 Moderate/Strong Inhibitors: ketoconazole, itraconazole, voriconazole, posaconazole, ritonavir, naproxen, clarithromycin, rifampicin, phenytoin, carbamazepine, phenobarbital, diltiazem, and St.John's Wort Part II Inclusion Criteria: * Patients with nonvalvular atrial fibrillation * Patients who was prescribed apixaban for primary or secondary prevention of stroke, transient ischemic attack, and systemic embolism. Exclusion Criteria: * Pregnant or lactating